Future of Glaucoma
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(Note that this was commentary originally authored in 2011-2012)
When I look into the future of glaucoma treatment, 3 things come to mind:
- Slow-release drug delivery systems that will avoid daily application of topical medications.
- Development of an ideal glaucoma surgery, which should be able to lower intraocular pressure (IOP) to mid- to low-teens via a small incision and should not take more than 10 minutes to perform, with complication rates less than 0.5% and quick visual recovery.
- Ganglion cell rehabilitation/regeneration with stem cell or similar technology.
This is easier said than done. So, I will detail those things that I think are achievable within the next 5 to 10 years.
Full-thickness filtration procedures, flat chambers, choroidal effusions, and cataract formations characterized glaucoma surgery in the first half of this century. Guarded filtration surgery and nonvalved and valved glaucoma drainage devices improved the surgical outcomes and decreased the complication rates in the second half of the 20th century. An explosion of new technology and techniques have taken glaucoma surgery to new heights in the first 10 years of the 21st century. Chances are that these changes will continue, with the ultimate goal of designing a glaucoma surgery that can be performed in 10 minutes via a 2- to 3-mm incision and have success rates similar to cataract and refractive surgery.
Traditional glaucoma surgeries divert the aqueous humor into the subconjunctival space. Failure from postoperative fibrosis and problems related to the bleb (pain and discomfort, leaky cystic blebs, bleb-related infections) are the bane of every glaucoma surgeon. The use of antifibrotic agents (eg, 5-fluorouracil [5-FU] and mitomycin C [MMC]) have increased the success of trabeculectomy operation while increasing the incidence of thin cystic blebs and bleb-related infections. The lack of standardization in the delivery of these drugs is one of the many problems that exist in the cur-rent trabeculectomy techniques. Future research should focus on standardizing the delivery techniques of these antifibrotic agents so as to achieve the maximum benefit while minimizing the side effects. New drugs and technologies are needed that help in modulating the bleb morphology while maintaining the overall health of the bleb. The use of antiangiogenesis drugs, such as Avastin (bevacizumab), and the new generation of collagen implants show early promise but await long-term results.
Glaucoma drainage devices (GDDs) have many advantages compared with traditional trabeculectomy such as fewer immediate postoperative complications, posterior location of the bleb, and significantly less incidence of bleb-related infections. However, they result in significantly higher-end IOP and failure rate secondary to bleb fibrosis. One -time use of anti-fibrotic agents does not appear to alter the success rate of GDDs. The development of antifibrotic, drug-coated GDDs or GDDs attached to slow-release drug (MMC) delivery systems might decrease the postoperative fibrosis and enhance the long-term success rate of current GDDs. If the creation of drug-coated GDDs results in IOPs comparable to trabeculectomy, then GDDs might displace trabeculectomy as the new gold standard in the foreseeable future. Animal studies using these GDDs attached to slow-release drug (MMC) delivery systems has demonstrated a significant decrease in the degree of postoperative bleb fibrosis. However, human clinical trails are still awaited.
The modification of surgeries that divert the aqueous humor into alter-native pathways such as the Schlemm’s canal (canaloplasty, trabeculotomy ab interno with the Trabectome, and iStent) and suprachoroidal space (Gold Shunt) have introduced more options to the glaucoma surgeon. Although long-term success rate of these new surgeries is not known, early results are encouraging. As more surgeons master these surgical techniques, these techniques may offer predictable results (lower IOP) with minimal complications, thus setting the stage for surgical intervention at an earlier stage in glaucoma patients who are burdened with multiple, expensive, topical glaucoma medications with numerous side effects. Although this kind of surgery might benefit the majority of patients with moderate glaucoma, there still will be a need for traditional surgery such as trabeculectomy or GDD implantation. Therefore, it is important that future research should also focus on further refinements of these age-old techniques to cater to patients with advanced glaucoma.
